Methods, apparatus, and systems for producing hydrogen from a fuel

ABSTRACT

Methods and apparatus for producing hydrogen are provided. The methods and apparatus utilize reforming catalysts in order to produce hydrogen gas. The reforming catalysts may be platinum group metals on a support material, and they may be located in a reforming reaction zone of a primary reactor. The support material may an oxidic support having a ceria zirconia promoter. The support material may be an oxidic support and a neodymium stabilizer. The support material may also be an oxidic support material and at least one Group IA, Group IIA, manganese, or iron metal promoter. The primary reactor may have a first and second reforming reaction zones. Upstream reforming catalysts located in the first reforming reaction zone may be selected to perform optimally under the conditions in the first reforming reaction zone. Downstream reforming catalysts located in the second reforming reaction zone may be selected to perform optimally under the conditions in the second reforming reaction zone.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.10/304,561, filed Nov. 26, 2002 (GMC 0019 PA/GP-302803).

BACKGROUND OF THE INVENTION

The present invention relates generally to the production of hydrogenfrom fuel and more particularly to primary reactors and methods forreforming hydrocarbons.

Many fuel cell systems use a fuel processing system to break down themolecules of a primary fuel to produce a hydrogen-rich gas streamcapable of powering the fuel cells. The fuel processing systemsgenerally have a primary reactor or reformer in which hydrocarbons areinitially broken down into various product gases including hydrogen.

In one type of reactor a steam reforming reaction is carried out byreacting a hydrocarbon fuel at high temperatures in the presence ofsteam on a suitable catalysts to give hydrogen, carbon monoxide, andcarbon dioxide. The reaction is highly endothermic. In another type ofreactor a partial oxidation reaction is carried out by reacting ahydrocarbon fuel in the presence of oxygen on a catalyst to producecarbon monoxide and hydrogen. The partial oxidation reaction isexothermic. Another possibility for reforming hydrocarbons is anautothermal reformer that combines catalytic partial oxidation and steamreforming wherein exothermic partial oxidation supplies the heat ofreaction required for endothermic steam reforming.

Autothermal reactors are particularly suitable for use in small scale,highly integrated fuel cell systems because fewer external components,such as heat sources or heat sinks, are required. However, the needstill exists for reactors that more efficiently produce hydrogen andthat may be used in a variety of fuel cell systems including smallscale, highly integrated fuel cell systems.

SUMMARY OF THE INVENTION

This need is met by the present invention which provides methods andapparatus for producing hydrogen. The methods and apparatus utilizereforming catalysts in order to produce hydrogen gas.

In accordance with one embodiment of the present invention, a method forproducing hydrogen gas from a fuel is provided. The method comprisesproviding an autothermal primary reactor having an inlet, an outlet, andat least one reforming reaction zone; providing at least one reformingcatalyst in the at least one reforming reaction zone, wherein the atleast one reforming catalyst comprises a platinum group metal on asupport material, and wherein the support material comprises an oxidicsupport and a promoter comprising ceria and zirconia, passing a reactantmixture of hydrocarbon fuel, oxygen, and steam over the at least onereforming catalyst to produce product gases, one of the product gasescomprising hydrogen. The method may further comprise subjecting theproduct gases to a water-gas shift reaction to convert carbon monoxideand water in the product gases to carbon dioxide leaving additionalhydrogen. The method may further comprise subjecting the product gasesto a final-stage scrubber to reduce carbon monoxide concentration in theproduct gases. The method may further comprise subjecting the productgases to a fuel cell stack to generate electricity.

In accordance with another embodiment of the present invention, a methodfor producing hydrogen gas from a fuel is provided. The method comprisesproviding an autothermal primary reactor having an inlet, an outlet, andat least one reforming reaction zone; providing at least one reformingcatalyst in the at least one reforming reaction zone, wherein the atleast one reforming catalyst comprises a platinum group metal on asupport material, and wherein the support material comprises an oxidicsupport and a stabilizing material comprising neodymium; and passing areactant mixture of hydrocarbon fuel, oxygen, and steam over the atleast one reforming catalyst to produce product gases, one of theproduct gases comprising hydrogen. The stabilizing material may furthercomprise lanthanum, and the oxidic support material may comprisealumina.

In accordance with another embodiment of the present invention, a methodfor producing hydrogen gas from a fuel is provided. The method comprisesproviding an autothermal primary reactor having an inlet, an outlet, andat least one reforming reaction zone; providing at least one reformingcatalyst in the at least one reforming reaction zone, wherein the atleast one reforming catalyst comprises a platinum group metal on anoxidic support material and at least one Group IA, Group IIA, manganese,or iron metal promoter, passing a reactant mixture of hydrocarbon fuel,oxygen, and steam over the at least one reforming catalyst to produceproduct gases, one of the product gases comprising hydrogen.

In accordance with another embodiment of the present invention, anapparatus for producing hydrogen gas from a fuel comprises anautothermal primary reactor having an inlet adapted to receive areactant stream comprising a hydrocarbon fuel, oxygen, and steam and anoutlet adapted to provide product gases, one of the gases comprisinghydrogen. The apparatus has at least one reforming reaction zonesituated between the inlet and the outlet and at least one reformingcatalyst in said at least one reforming reaction zone. The at least onereforming catalyst comprises a platinum group metal on a supportmaterial, and the support material comprises an oxidic support andpromoter comprising ceria and zirconia.

In accordance with another embodiment of the present invention, anapparatus for producing hydrogen gas from a fuel comprises anautothermal primary reactor having an inlet adapted to receive areactant stream comprising a hydrocarbon fuel, oxygen, and steam and anoutlet adapted to provide product gases, one of the gases comprisinghydrogen. The apparatus has at least one reforming reaction zonesituated between the inlet and the outlet and at least one reformingcatalyst in said at least one reforming reaction zone. The at least onereforming catalyst comprises a platinum group metal on a support, andthe support comprises an oxidic support and a stabilizing materialcomprising neodymium. The stabilizing material may further compriselanthanum.

In accordance with another embodiment of the present invention, anapparatus for producing hydrogen gas from a fuel comprises anautothermal primary reactor having an inlet adapted to receive areactant stream comprising a hydrocarbon fuel, oxygen, and steam and anoutlet adapted to provide product gases, one of the gases comprisinghydrogen. The apparatus has at least one reforming reaction zonesituated between the inlet and the outlet and at least one reformingcatalyst in said at least one reforming reaction zone. The at least onereforming catalyst comprises at least one platinum group metal on anoxidic support material and at least one Group IA, Group IIA, manganese,or iron metal promoter.

In accordance with yet another embodiment, a method for producinghydrogen gas from a fuel is provided. The method comprises providing anautothermal primary reactor having an inlet, an outlet, a firstreforming reaction zone, and a second reforming reaction zone, whereinthe first reforming reaction zone is proximate to the inlet and the dsecond reforming reaction zone is proximate to the outlet; providing atleast one upstream reforming catalyst in the first reforming reactionzone, wherein the at least one upstream reforming catalyst is selectedto perform optimally in conjunction with operating conditions in thefirst reforming reaction zone; providing at least one downstreamreforming catalyst in the second reforming reaction zone, wherein the atleast one downstream reforming catalyst is selected to perform optimallyin conjunction with operating conditions in the second reformingreaction zone; and passing a reactant mixture of hydrocarbon fuel,oxygen, and steam through the first and second reforming reaction zonessuch that reforming reactions occur therein, thereby forming productgases, one of which comprises hydrogen.

In accordance with another embodiment, an apparatus for producinghydrogen gas from a fuel comprises an autothermal primary reactor havingan inlet adapted to receive a reactant stream comprising a hydrocarbonfuel, oxygen, and steam and an outlet adapted to provide product gases,one of said gases comprising hydrogen. The apparatus has a firstreforming reaction zone proximate to the inlet and a second reformingreaction zone proximate to the outlet. At least one upstream reformingcatalyst is contained in the first reforming reaction zone, and the atleast one upstream reforming catalyst is selected to perform optimallyin conjunction with operating conditions in the first reforming reactionzone. At least one downstream reforming catalyst is contained in thesecond reforming reaction zone, and the at least one downstreamreforming catalyst is selected to perform optimally in conjunction withoperating conditions in the second reforming reaction zone.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of the preferred embodiments of thepresent invention can be best understood when read in conjunction withthe following drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is a schematic illustration of a fuel processing system and fuelcell stack.

FIG. 2 is a schematic illustration of a primary reactor.

FIG. 3 is an illustration of a monolithic structure.

FIG. 4 is a schematic illustration of a vehicle having a fuel processingsystem and a fuel stack.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates an exemplary fuel cell system comprising a fuelprocessing system 11 with a primary reactor 10, a water-gas shiftreactor 26, and a final stage scrubber 28. The fuel processing system 11provides the fuel cell stack 30 with a source of hydrogen. In theprimary reactor 10, a reactant mixture 22 that may contain a hydrocarbonfuel stream and an oxygen-containing stream is flowed into the primaryreactor 10. The oxygen-containing stream may comprise air, steam, andcombinations thereof. The reactant mixture 22 may be formed by mixing ahydrocarbon fuel with a preheated air and steam input stream beforeflowing the reactant mixture into the primary reactor. After thereactant mixture 22 is flowed into the primary reactor 10, the reactantmixture 22 passes over at least one reaction zone having at least onereforming catalyst and product gas stream 24 containing hydrogen isproduced catalytically. The primary reactor 10 is generally anautothermal reactor in which hydrogen is produced by combined catalyticpartial oxidation and steam reforming reactions but may alternativelycomprise any suitable reactor configuration.

In one embodiment, the product gas stream 24 exiting the primary reactor10 may comprise hydrogen, carbon dioxide, carbon monoxide, and tracecompounds, and water in the form of steam. To reduce carbon monoxide andincrease efficiency, product gas stream 24 may enter a water gas-shiftreactor 26. Oxygen from introduced water converts the carbon monoxide tocarbon dioxide leaving additional hydrogen. For optimum efficiency, thewater gas-shift reactor 26 may run with an inlet temperature betweenabout 250° C. and about 400° C. The reduction of carbon monoxide toacceptable concentration levels takes place in the final stage scrubber28. For example, air may be added to the final stage scrubber 28 tosupply the oxygen needed to convert most of the remaining carbonmonoxide to carbon dioxide. Alternatively, carbon monoxide in theproduct gas stream 24 may be absorbed by a carbon monoxide absorbingmaterial provided in the final stage scrubber 28 and may be swept out bypurge gases with variable pressure. The operating temperatures in thefinal stage scrubber 28 may range from about 50° C. to about 200° C.

The carbon monoxide purged product stream 24′ exiting the final stagescrubber 28 is then fed into a fuel cell stack 30. As used herein, theterm fuel cell stack refers to one or more fuel cells to form anelectrochemical energy converter. As is illustrated schematically inFIG. 1, the electrochemical energy converter may have an anode side 1and a cathode side 32 separated by diffusion barrier layer 35. Thecarbon monoxide purged product stream 24′ is fed into the anode side 1of the fuel cell stack 30. An oxidant stream 36 is fed into the cathodeside 32. The hydrogen from the carbon monoxide purged product stream 24′and the oxygen from the oxidant stream 36 react in the fuel cell stack30 to produce electricity for powering a load 38. A variety ofalternative fuel cell designs are contemplated be present inventionincluding designs that include a plurality of anodes 1, a plurality ofcathodes 32, or any fuel cell configuration where hydrogen is utilizedin the production of electricity.

Referring to FIG. 2, a primary reactor 10 is illustrated schematically.The primary reactor 10 has an inlet 12, an outlet 14, and a reformingreaction zone 16. A reactant mixture 22 may enter the primary reactor 10through the inlet 12. The reforming reaction zone 16 generally containsat least one reforming catalyst. The reactant mixture 22 generallypasses through the reforming reaction zone 16 over at least onereforming catalyst, and product gases 24 are catalytically produced. Oneof the product gases 24 comprises hydrogen, and the product gases 24generally exit through the outlet 14. The outlet 14 may be adapted toprovide product gases, one of which is hydrogen. The primary reactor 10is generally an autothermal reactor. It will be understood by thosehaving skill in the art that primary reactor 10 may be of any suitablestructure that allows a reactant stream including a fuel to be directedthrough a fuel reforming zone including at least one reforming catalyst.

The reforming catalyst generally comprises at least one platinum groupmetal catalyst on an oxidic support. The term “reforming catalyst” asused herein includes catalysts, catalyst support materials, promoters,stabilizers, and the like. The oxidic support may be alumina, silica,titania, ceria, zirconia, or mixed oxides thereof. The reformingcatalysts may be prepared using any suitable techniques. Preparationtechniques for preparing supported catalysts are well known in the art.It will be understood by those having skill in the art that there may bemore than one reforming catalyst in the reforming reaction zone 16.

In one embodiment, the reforming catalyst comprises platinum and rhodiumon an oxidic support. For example, the rhodium and platinum may besupported on alumina or ceria zirconia. The rhodium and platinum mayalso be supported on alumina promoted with ceria zirconia as will bediscussed hereinafter. The ratio of rhodium to platinum may be betweenabout 10:1 to 1:10 and is more preferably between about 3:1 to 1:3. Thereforming catalyst may have a lower light-off temperature than rhodiumbased reforming catalysts. A catalyst with a lower light-off temperatureallows the primary reactor 10 to be started with a lower amount ofenergy input. Therefore, the reforming catalyst may provide fastlight-off ability.

The reforming catalysts containing platinum and rhodium may be preparedusing any suitable method. For example, co-impregnation may be usedwherein suitable metal salts are made into a solution such that thevolume of the solution is sufficient to fill the entire pore volume ofthe support material. The solution is added to the support material, andthe mixture is mixed thoroughly and dried and calcined. Alternatively,the metal species may be impregnated sequentially. For example, theplatinum may be impregnated subsequent to the rhodium. Another suitablemethod for preparing the reforming catalysts is co-deposition whereinthe support material is dispersed in a slurry containing suitable metalsalts. A base is added to the slurry to deposit the metals onto thesupport materials, and the catalyst is dried and calcined. It isgenerally preferable for the platinum and rhodium to be depositedtogether rather than be present as a physical mix.

In accordance with another embodiment, the reforming catalyst maycomprise a platinum group metal on an oxidic support stabilized withneodymium, lanthanum, or combinations thereof. The neodymium andlanthanum are generally incorporated into the lattice structure of thesupport material. The neodymium, lanthanum, or neodymium and lanthanumare generally present in an amount of about 1% to about 8% by weight ofthe support material. The oxidic support material may be alumina, ceriazirconia, or any other suitable support. The presence of the stabilizingmaterial in the support may enhance the thermal durability of thesupport and may assist the support in retaining porosity.

It will be understood by those having skill in the art that variousformulations are possible for the reforming catalyst. For example, thereforming catalyst may comprise 1% rhodium supported on lanthanumstabilized alumina. The reforming catalyst may also comprise 1% or 2%rhodium supported on ceria zirconia that is lanthanum and neodymiumstabilized. The reforming catalyst may comprise 2% rhodium on neodymiumand lanthanum stabilized alumina that is promoted with 30% ceriazirconia as described herein.

The reforming catalyst containing lanthanum and neodymium stabilizersmay be formed in any suitable manner. For example, the lanthanum andneodymium are generally incorporated into the support material beforethe catalyst metals are added to the support. The support material maybe formed by co-precipitation wherein the support material is dispersedin a slurry containing suitable metal salts. A base is added to theslurry to precipitate the metals onto the support materials, and thecatalyst is dried and calcined. The catalyst metals may be added to thesupport material containing lanthanum and neodymium by any suitablemethod such as impregnation.

In yet another embodiment, the reforming catalyst may comprise aplatinum group metal on an oxidic support with a ceria and zirconiapromoter deposited on the support. The oxidic support material may bealumina. The ceria and zirconia may comprise between about 10% to about60% by weight of the support material, and the ceria and zirconia moregenerally comprise between about 20% to about 40% by weight of thesupport material. The ratio of ceria to zirconia in the reformingcatalyst is generally between about 80:20 to about 20:80. The platinumgroup metal may comprise rhodium, and the rhodium may be present in anamount of about 1% to about 3% by weight of the reforming catalyst. Theplatinum group metal may also comprise platinum. The support materialmay be stabilized with lanthanum, neodymium or combinations thereof asdescribed herein. The reforming catalyst having a support materialpromoted with ceria and zirconia may exhibit improved activity and theability to reform large concentrations of hydrocarbon fuel.

It will be understood by those having skill in the art that the termpromoter is not used herein to imply that the ceria and zirconia areincorporated into the structure of the support material. Rather, theterm promoter is used to describe the action of the presence of ceriazirconia on the support material as promoting reforming reactions. Theceria and zirconia of the present invention are not generallyincorporated into the structure of the support material. Instead, theceria and zirconia are deposited on the support material.

It will be further understood by those having skill in the art thatvarious formulations are possible for the reforming catalyst. Forexample, the reforming catalyst may comprise 1% rhodium supported on analumina support with 10%, 20%, 30%, or 40% ceria zirconia by weight ofthe support. The ceria and zirconia may have a ratio of 75:25.Alternatively, the reforming catalyst may comprise 2% or 3% rhodium onan alumina support with 30% ceria zirconia by weight of the support, andthe activity of the reforming catalyst may improve with increasedrhodium loading. The reforming catalyst may comprise 1% or 2% rhodium onan alumina support and 30% of a ceria zirconia and be lanthanumneodymium stabilized, wherein the promoter and stabilizer are present inan atomic ratio of Ce_(0.20)Zr_(0.73)Nd_(0.05)La_(0.02).

The reforming catalysts containing ceria and zirconia may be prepared inaccordance with any suitable method. For example, the ceria and zirconiamay be deposited on a support material by a sol-gel route. Sols of ceriaand zirconia are stabilized by counter ions such as nitrate and acetate.The sols are added to a slurry of a support material, and a base such asa 1M ammonia solution is added to the slurry. The product is then washedseveral times and dried, e.g. at 120° C., and calcined, e.g. at 800° C.

In another embodiment, the reforming catalyst comprises a platinum groupmetal on a support promoted with a Group IA, Group IIA, manganese, oriron metal promoter. The atomic ratio of the Group IA, Group IIA,manganese, or iron metal promoter to the platinum group metal may bebetween about 10:1 to about 2:1. The promoter may be selected from iron,manganese, lithium, or potassium, and the support may comprise alumina.The Group IA, Group IIA, manganese or iron metal promoter may beincorporated into the structure of the support. The platinum group metalmay comprise rhodium, and the platinum group metal may further compriseplatinum as discussed above. Additionally, the support may be promotedwith ceria zirconia as discussed above. The reforming catalysts mayexhibit improved activity, durability, or a combination thereof. Forexample, the reforming catalysts may exhibit the ability to steam reformlow concentrations of fuel and short chain hydrocarbons effectively.

It will be understood by those having skill in the art that the termpromoter is not used herein to imply that the Group IA, Group IIA,manganese, or iron metal promoters are incorporated into the structureof the support material. Rather, the term promoter is used to describethe action of the presence of the Group IA, Group IIA, manganese, andiron metal promoters as promoting reforming reactions.

It will be understood by those having skill in the art, that variouscombinations are possible for a reforming catalyst comprising a platinumgroup metal on a support promoted with a Group IA, Group IIA, manganeseor iron metal promoter. For example, when iron is chosen as thepromoter, the reforming catalyst may comprise 1% rhodium on aluminapromoted with iron. Alternatively, the reforming catalyst may comprise0.32%, 1%, or 5% iron by weight of the reforming catalyst, and thereforming catalyst may further comprise 1% rhodium on alumina promotedwith ceria zirconia. When manganese is chosen as the promoter, thereforming catalyst may comprise 1% rhodium on alumina promoted withmanganese. When lithium is chosen as the promoter, the reformingcatalyst may comprise lithium and 2% rhodium on alumina promoted withceria zirconia. In this case, the atomic ratio of Li:Rh is 1:10. Whenpotassium is chosen as the promoter, the reforming catalyst may comprisepotassium and 2% rhodium on alumina promoted with ceria zirconia, andthe atomic ratio of K:Rh is 1:10.

The reforming catalysts containing Group IA, Group IIA, manganese, oriron metal promoters may be prepared using any suitable method. Forexample, co-impregnation may be used wherein suitable metal salts aremade into a solution such that the volume of the solution is sufficientto fill the entire pore volume of the support material. The solution isadded to the support material, and the mixture is mixed thoroughly anddried and calcined. Alternatively, the metal species may be impregnatedsequentially. For example, the platinum group metal may be impregnatedsubsequent to the Group IA, Group IIA, manganese, or iron metal promoterbeing impregnated. Another suitable method for preparing the reformingcatalysts is co-deposition wherein the support material is dispersed ina slurry containing suitable metal salts. A base is added to the slurryto deposit the metals onto the support materials, and the catalyst isdried and calcined.

The reforming catalysts of the present invention may be carried on acarrier structure located in the reforming reaction zone 16. Anysuitable carrier structure may be used. For example, referring to FIG.3, a monolithic structure 40 is illustrated. The monolithic structure 40generally has a body 42 and a plurality of channels 44 running throughthe body of 42. The channels 44 may be of any suitable shape andconfiguration, and the channels are generally designed to provide anincreased surface area on which the reforming catalysts may bedeposited. For example, the channels 44 are illustrated as having ahoneycomb configuration. It will be understood by those having skill inthe art that the number of channels 44 per unit area may be increased ordecreased as desired and that the loading of the reforming catalyst ontothe carrier structure 40 may be modified as desired. The monolithicstructure 40 may be formed using any suitable material, including, butnot limited to ceramic, metal, open-cell ceramic foam, open-cell metalfoam, and combinations thereof. Methods of coating or depositingreforming catalysts on monolithic structures are well known in the art.

Referring again to FIG. 2, the primary reactor 10 may have first andsecond reforming reaction zones 18 and 20. The first reaction zone 18 islocated proximate to the inlet 12, and the second reaction zone 20 islocated proximate to the outlet 14. Generally, the reactant mixture 22passes through the first reaction zone 18 before passing through thesecond reaction zone 20. The first reaction zone 18 has at least oneupstream reforming catalyst contained therein. The second reaction zone20 has at least one downstream reforming catalyst contained therein.

The first and second reforming reaction zones 18, 20 generally are notsubject to the same operating conditions. For example, the firstreaction zone 18 may operate at a higher temperature than the secondreaction zone 20. Additionally, the concentration of the reactantmixture 22 may be highest in the first reaction zone 18, and more largehydrocarbons may be present in the first reaction zone. The reformingreaction starts in the first reaction zone 18, and it may be desirablefor the reforming reaction to light-off quickly to aid in a faststart-up of the primary reactor 10. Because the first and secondreaction zones 18, 20 may operate under different conditions, theupstream reforming catalyst may be selected to perform optimally underthe conditions of the first reaction zone 18. Similarly, the downstreamreforming catalyst may be selected to perform optimally under theconditions of the second reaction zone 20. When the upstream anddownstream reforming catalysts are selected to perform optimally, theymay have a synergistic effect on the operation of the primary reactor 10and improve the efficiency of the primary reactor.

The upstream reforming catalyst is generally selected to have fastlight-off ability, thermal durability, or the ability to reform highconcentrations of fuel. Additionally, the upstream reforming catalystmay be selected to have one or more of the above properties. It will beunderstood that the first reforming catalyst may comprise more than onereforming catalyst, and it will be further understood that eachreforming catalyst may have one or more of the properties listed above.Therefore, more than one upstream catalyst may be present, and theupstream catalysts may have different properties or more than oneproperty. Any suitable catalyst having the desired property orproperties may be used.

In one embodiment, one of the upstream reforming catalysts may be aplatinum and rhodium catalyst on an oxidic support as already describedherein. This catalyst provides fast light-off ability. In anotherembodiment, one of the upstream reforming catalysts may comprise aplatinum group metal on an oxidic support stabilized with lanthanum,neodymium, or combinations thereof as described herein. This catalystprovides thermal durability. In another embodiment, one of the upstreamcatalysts may comprise a platinum group metal on an oxidic supportpromoted with ceria and zirconia as described herein. This catalystprovides the ability to reform large concentrations of fuel. It will beunderstood that these reforming catalysts may be combined as desired.For example, in one embodiment, the catalyst may comprise at least oneplatinum group metal on a support stabilized with lanthanum, neodymium,or combinations thereof and promoted with ceria and zirconia.

The downstream reforming catalyst may be any suitable catalyst thatperforms well under the conditions of the second reaction zone 20. Itwill be understood that the downstream reforming catalyst may be morethan one catalyst having one or more different properties. In oneembodiment, the downstream reforming catalyst may comprises a platinumgroup metal on an oxidic support with at least one Group IA, Group IIA,manganese or iron metal promoter as described herein. This catalystprovides the ability to reform low concentrations of fuel.

The first and second reaction zones 18, 20 may be defined by amonolithic structure 40 as illustrated in FIG. 3. The monolithic carriermay be a single body 42 defining the first and second reaction zones 18,20. Alternatively, the first reaction zone 18 may be defined by a firstmonolithic structure, and the second reaction zone 20 may be defined bya second monolithic structure. It will be understood by those havingskill in the art that the first and second monolithic structures mayhave the same number of channels 44 or different numbers of channels.The upstream and downstream catalysts may be coated on the monolithicstructure in any suitable manner.

A method for producing hydrogen gas from a fuel may comprise providingan primary reactor having an inlet, an outlet, and at least onereforming reaction zone; providing a least one reforming catalyst in thereforming reaction zone; directing a hydrocarbon fuel stream into thereactor; and flowing an oxygen-containing stream into the reactor, suchthat the fuel stream and the oxygen-containing stream are exposed to thereforming reaction zone and a reforming reaction occurs, thereby formingproduct gases, one of which is hydrogen. The method may compriseproviding an autothermal primary reactor having an inlet, an outlet, andat least one reforming reaction zone; providing at least one reformingcatalyst in the least one reforming reaction zone; passing a reactantmixture of hydrocarbon fuel, oxygen, and steam over the reformingcatalyst to produce product gases, one of said product gases comprisinghydrogen. The method may further comprise providing an autothermalprimary reactor having an inlet, an outlet, a first reforming reactionzone proximate to the inlet, a second reforming reaction zone proximateto the outlet; providing at least one upstream reforming catalyst in thefirst reforming reaction zone; providing at least one downstreamreforming catalyst in the second reforming reaction zone; and passing areactant mixture of hydrocarbon fuel, oxygen, and steam through thefirst and second reforming reaction zones such that reforming reactionsoccur therein, thereby forming product gases, one of which compriseshydrogen.

Referring to FIGS. 1, 2, and for, the fuel processing system 11 of thepresent invention may be used to provide a vehicle body 50 with motivepower. The fuel processing system 11 may provide at least one fuel stack30 with a source of hydrogen gas. The fuel stack 30 may be utilized toat least partially provide the vehicle body 50 with motive power. Itwill be understood by those having skill in the art that fuel stack 30and fuel processing system 11 are shown schematically and may be used orplaced in any suitable manner within the vehicle body 50.

It will be obvious to those skilled in the art that various changes maybe made without departing from the scope of the invention, which is notto be considered limited to what is described in the specification.

1. An apparatus for producing hydrogen gas from a fuel, comprising: anautothermal primary reactor having an inlet adapted to receive areactant stream comprising a hydrocarbon fuel, oxygen, and steam and anoutlet adapted to provide product gases, one of said gases comprisinghydrogen; a first reforming reaction zone characterized by a firstlight-off temperature proximate to said inlet; a second reformingreaction zone proximate to said outlet; at least one upstream reformingcatalyst comprised of platinum and rhodium in said first reformingreaction zone, wherein a sufficient amount of platinum is present withinsaid at least one upstream reforming catalyst to lower said firstlight-off temperature below that of a rhodium based reforming catalystwithout a substantial amount of platinum and wherein said at least oneupstream reforming catalyst is selected to is selected to performoptimally in conjunction with operating conditions in said firstreforming reaction zone; and at least one downstream reforming catalystin said second reforming reaction zone, wherein said operatingconditions in said first reforming reaction zone are characterized by atemperature higher than the temperature of said second reformingreaction zone and wherein said at least one downstream reformingcatalyst is selected to perform optimally in conjunction with operatingconditions in said second reforming reaction zone.
 2. The apparatus asclaimed in claim 1 wherein said operating conditions in said firstreforming reaction zone are characterized by concentrations of fuel thatare higher than the concentrations of fuel in said second reformingreaction zone.
 3. The apparatus as claimed 1 wherein said operatingconditions in said second reforming reaction zone are characterized byconcentrations of fuel that are lower than concentrations of fuel insaid first reforming reaction zone.
 4. The apparatus as claimed in claim1 wherein said upstream reforming catalyst comprises one or morecatalysts selected to provide fast light-off ability, thermaldurability, or the ability to reform high concentrations of fuel, andcombinations thereof, and wherein said downstream reforming catalystcomprises one or more catalysts selected to provide the ability toreform low concentrations of fuel.
 5. The apparatus as claimed in claim1 wherein said upstream reforming catalyst comprises one or morecatalysts selected to provide fast light-off ability.
 6. The apparatusas claimed in claim 1 wherein said upstream reforming catalyst comprisesone or more catalysts selected to provide thermal durability.
 7. Theapparatus as claimed in claim 1 wherein said upstream reforming catalystcomprises one or more catalysts selected to provide the ability toreform high concentrations of fuel.
 8. The apparatus as claimed in claim1 wherein said upstream reforming catalyst comprises one or morecatalysts selected to provide fast light-off ability and thermaldurability.
 9. The apparatus as claimed in claim 8 wherein said upstreamreforming catalyst comprises one or more catalysts selected to providesaid fast light-off ability and one or more different catalysts selectedto provide said thermal durability.
 10. The apparatus as claimed inclaim 1 wherein said upstream reforming catalyst comprises one or morecatalysts selected to provide fast light-off ability and the ability toreform high concentrations of fuel.
 11. The apparatus as claimed inclaim 10 wherein said upstream reforming catalyst comprises one or morecatalysts selected to provide said fast light-off ability and one ormore different catalysts selected to provide said ability to reform highconcentrations of fuel.
 12. The apparatus as claimed in claim 1 whereinsaid upstream reforming catalyst comprises one or more catalystsselected to provide thermal durability and the ability to reform highconcentrations of fuel.
 13. The apparatus as claimed in claim 12 whereinsaid upstream reforming catalyst comprises one or more catalystsselected to provide said thermal durability and one or more differentcatalysts selected to provide said ability to reform high concentrationsof fuel.
 14. The apparatus as claimed in claim 1 wherein said upstreamreforming catalyst comprises one or more catalysts selected to providethermal durability, fast light-off ability, and the ability to reformhigh concentrations of fuel.
 15. The apparatus as claimed in claim 14wherein said upstream reforming catalyst comprises one or more catalystsselected to provide fast light-off ability, one or more differentcatalysts selected to provide said thermal durability, and one or moredifferent catalysts selected to provide the ability to reform highconcentrations of fuel.
 16. The apparatus as claimed in claim 1 whereinsaid upstream reforming catalyst comprises a catalyst material on asupport material, and wherein said catalyst material comprises rhodiumand platinum and said support material comprises an oxidic support. 17.The apparatus as claimed in claim 16 wherein said upstream reformingcatalyst provides fast light-off ability.
 18. The apparatus as claimedin claim 1 wherein said upstream reforming catalyst comprises at leastone platinum group metal on a support, and wherein said support materialcomprises an oxidic support and a stabilizing material comprisinglanthanum, neodymium, and combinations thereof.
 19. The apparatus asclaimed in claim 18 wherein said upstream reforming catalyst providesthermal durability.
 20. The apparatus as claimed in claim 18 whereinsaid at least one platinum group metal comprises rhodium and platinum.21. The apparatus as claimed in claim 1 wherein said upstream reformingcatalyst comprises at least one platinum group metal on a supportmaterial, and wherein said support material comprises an oxidic supportand a promoter comprising ceria and zirconia.
 22. The apparatus asclaimed in claim 21 wherein said upstream reforming catalyst providesthe ability to reform high concentrations of fuel.
 23. The apparatus asclaimed in claim 21 wherein said at least one platinum group metalcomprises rhodium and platinum.
 24. The apparatus as claimed in claim 1wherein said upstream reforming catalyst comprises at least one platinumgroup metal on a support, and wherein said support material comprises anoxidic support, a promoter comprising ceria and zirconia, and astabilizing material comprising lanthanum, neodymium, and combinationsthereof.
 25. The apparatus as claimed in claim 1 wherein said downstreamreforming catalyst comprises a platinum group metal on an oxidic supportmaterial and at least one Group I, Group II, manganese, or iron metalpromoter.
 26. The apparatus as claimed in claim 1 wherein said first andsecond reaction zones are defined by a monolithic structure.
 27. Theapparatus as claimed in claim 26 wherein said monolithic structure ismade from ceramic, metal, open-cell ceramic foam, open-cell metal foamand combinations thereof.
 28. The apparatus as claimed in claim 1wherein said first reaction zone is defined by a first monolithicstructure, and wherein said second reaction zone is defined by a secondmonolithic structure.
 29. A fuel cell system comprising: a fuel cellstack provided with a source of hydrogen gas; and a fuel processingsystem for providing said hydrogen gas, said fuel processing systemcomprising an autothermal primary reactor wherein: said autothermalprimary reactor has an inlet adapted to receive a reactant streamcomprising a hydrocarbon fuel, oxygen, and steam and an outlet adaptedto provide product gases, one of said gases comprising hydrogen, saidautothermal primary reactor has a first reforming reaction zonecharacterized by a first light-off temperature proximate to said inlet,said autothermal primary reactor has a second reforming reaction zoneproximate to said outlet, said autothermal primary reactor has at leastone upstream reforming catalyst comprised of platinum and rhodium insaid first reforming reaction zone, wherein a sufficient amount ofplatinum is present within said at least one upstream reforming catalystto lower said first light-off temperature below that of a rhodium basedreforming catalyst without a substantial amount of platinum and whereinsaid at least one upstream reforming catalyst is selected to performoptimally in conjunction with conditions in said first reformingreaction zone, and said autothermal primary reactor has at least onedownstream reforming catalyst in said second reforming reaction zone,wherein said operating conditions in said first reforming reaction zoneare characterized by a temperature higher than the temperature of saidsecond reforming reaction zone and wherein said at least one downstreamreforming catalyst is selected perform optimally in conjunction withconditions in said second reforming reaction zone.
 30. A vehiclecomprising: a vehicle body; at least one fuel cell stack provided with asource of hydrogen gas, wherein said at least one fuel cell stack atleast partially provides said vehicle body with motive power; and a fuelprocessing system for providing said hydrogen gas, said fuel processingsystem comprising an autothermal primary reactor wherein: saidautothermal primary reactor has an inlet adapted to receive a reactantstream comprising a hydrocarbon fuel, oxygen, and steam and an outletadapted to provide product gases, one of said gases comprising hydrogen,said autothermal primary reactor has a first reforming reaction zonecharacterized by a first light-off temperature proximate to said inlet,said autothermal primary reactor has a second reforming reaction zoneproximate to said outlet, said autothermal primary reactor has at leastone upstream reforming catalyst comprised of platinum and rhodium insaid first reforming reaction zone, wherein a sufficient amount ofplatinum is present within said at least one upstream reforming catalystto lower said first light-off temperature below that of a rhodium basedreforming catalyst without a substantial amount of platinum and whereinsaid at least one upstream reforming catalyst is selected to performoptimally in conjunction with conditions in said first reformingreaction zone, and said autothermal primary reactor has at least onedownstream reforming catalyst in said second reforming reaction zone,wherein said operating conditions in said first reforming reaction zoneare characterized by a temperature higher than the temperature of saidsecond reforming reaction zone and wherein said at least one downstreamreforming catalyst is selected perform optimally in conjunction withconditions in said second reforming reaction zone.